Sony XDP-U50D Digital Car Stereo Pre-Amplifier - Customize Sound From Your Car's Audio System! Sony XDP-U50D Digital Car Stereo Pre-Amplifier General Features: Digital Car Stereo Pre-Amplifier Ten (10) Preset digital surround modes (Hall, Concert, Opera, Jazz club, Church) Optimum listening position can be selected from five (5) different settings DSP file function enables the discs to be played in customized DSP mode LSM (Last Sound Memory) function enable programs to be played with the preset surround mode